:root {
  --ink: #0b0e0f;
  --panel: #12171a;
  --line: #262e31;
  --paper: #e8ecea;
  --mute: #8a9598;
  --pid: #3fb8a9;
  --sld: #e3a43a;
  --logic: #8fa8ff;

  --f-display: "Zen Kaku Gothic New", "Hiragino Sans", "Yu Gothic", sans-serif;
  --f-body: "IBM Plex Sans JP", "Hiragino Sans", "Yu Gothic", sans-serif;
  --f-mono: "IBM Plex Mono", ui-monospace, monospace;

  --gutter: clamp(16px, 4vw, 56px);
  --max: 1240px;
  --edge: max(var(--gutter), calc((100vw - var(--max)) / 2 + var(--gutter)));
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--f-body);
  font-size: 16px;
  line-height: 1.8;
  -webkit-font-smoothing: antialiased;
  line-break: strict;
}
a { color: inherit; }
:focus-visible { outline: 2px solid var(--pid); outline-offset: 3px; }

.skip { position: absolute; left: -9999px; }
.skip:focus { left: 16px; top: 16px; z-index: 20; background: var(--paper); color: var(--ink); padding: 8px 12px; }

/* ---------- header ---------- */
.site-header {
  position: fixed; inset: 0 0 auto 0; z-index: 10;
  display: flex; align-items: center; justify-content: space-between;
  height: 64px; padding: 0 var(--edge);
  background: rgba(11, 14, 15, 0.72);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.brand { display: flex; align-items: center; gap: 10px; text-decoration: none; font-family: var(--f-mono); font-weight: 500; letter-spacing: 0.06em; font-size: 16px; }
.brand-mark { width: 22px; height: 22px; fill: none; stroke: var(--paper); stroke-width: 1.6; }
.nav { display: flex; align-items: center; gap: 28px; font-size: 14px; }
.nav a { text-decoration: none; color: var(--mute); transition: color .2s; }
.nav a:hover { color: var(--paper); }
.nav .nav-cta { color: var(--ink); background: var(--paper); padding: 6px 16px; }
.nav .nav-cta:hover { color: var(--ink); background: #fff; }

/* ---------- shared ---------- */
.eyebrow {
  font-family: var(--f-mono); font-size: 12px; letter-spacing: 0.22em; text-transform: uppercase;
  color: var(--mute); margin: 0 0 20px;
}
h1, h2, h3 { font-family: var(--f-display); font-weight: 700; margin: 0; letter-spacing: -0.01em; word-break: auto-phrase; }
h1 { font-size: clamp(36px, 6.2vw, 88px); line-height: 1.12; }
h2 { font-size: clamp(32px, 4.6vw, 64px); line-height: 1.15; }
.h2-long { font-size: clamp(26px, 3vw, 42px); line-height: 1.4; max-width: 24em; }
h3 { font-size: 22px; font-weight: 500; }

.btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 48px; padding: 0 24px; font-size: 15px; text-decoration: none;
  border: 1px solid var(--paper); transition: background .2s, color .2s;
}
.btn-primary { background: var(--paper); color: var(--ink); }
.btn-primary:hover { background: #fff; }
.btn-ghost { color: var(--paper); }
.btn-ghost:hover { background: rgba(232, 236, 234, 0.08); }
.btn-lg { min-height: 56px; padding: 0 32px; font-size: 16px; }

.sw { display: inline-block; width: 18px; height: 2px; vertical-align: middle; margin-right: 10px; }
.sw-pid { background: var(--pid); }
.sw-sld { background: var(--sld); }
.sw-logic { background: var(--logic); }

/* ---------- hero ---------- */
.hero {
  position: relative; min-height: min(100svh, 960px);
  display: flex; align-items: flex-end;
  padding: 120px var(--edge) 96px;
  overflow: hidden;
  border-bottom: 1px solid var(--line);
}
/* 写真は彩度と明るさを落とし、その上にグラフを重ねる */
.hero-photo { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; object-position: 70% center; filter: grayscale(0.6) brightness(0.5); }
#hero-graph { position: absolute; inset: 0; width: 100%; height: 100%; }
.hero::after {
  content: ""; position: absolute; inset: 0; pointer-events: none;
  background: linear-gradient(90deg, rgba(11,14,15,0.92) 0%, rgba(11,14,15,0.55) 45%, rgba(11,14,15,0) 75%);
}
.hero-inner { position: relative; z-index: 1; max-width: 880px; }
.lead { font-size: clamp(16px, 1.4vw, 19px); color: #c5cdcb; max-width: 36em; margin: 32px 0 40px; }
.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

/* ---------- sections ---------- */
.section {
  max-width: var(--max); margin: 0 auto;
  padding: clamp(96px, 12vw, 160px) var(--gutter);
  border-bottom: 1px solid var(--line);
}
.section-head { margin-bottom: clamp(48px, 6vw, 80px); }
.section-lead { max-width: 34em; color: #c5cdcb; margin: 28px 0 0; font-size: 17px; }

/* platform */
.platform { display: grid; grid-template-columns: 1.15fr 1fr; gap: clamp(32px, 6vw, 96px); align-items: center; }
.layers-figure svg { width: 100%; height: auto; display: block; }
.platform-text h3 { font-size: clamp(22px, 2.4vw, 30px); font-weight: 700; line-height: 1.4; margin-bottom: 24px; }
.platform-text p { margin: 0; color: #c5cdcb; font-size: 17px; }
.more { display: inline-block; margin-top: 28px; font-size: 15px; text-decoration: none; border-bottom: 1px solid var(--pid); padding-bottom: 2px; }
.more::after { content: " →"; }
.more:hover { color: #fff; }

/* 三つの図面のタイル：P&ID と SLD は写真、LOGIC は写真がないのでグラフで見せる */
.tiles { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); margin-bottom: clamp(80px, 10vw, 140px); }
.tile { position: relative; aspect-ratio: 3 / 4; overflow: hidden; background: var(--ink); display: flex; align-items: flex-end; }
.tile img, .tile-net { position: absolute; inset: 0; width: 100%; height: 100%; object-fit: cover; }
.tile img { filter: grayscale(0.5) brightness(0.45); transition: filter .4s; }
.tile:hover img { filter: grayscale(0.2) brightness(0.6); }
.tile::after { content: ""; position: absolute; inset: 0; background: linear-gradient(0deg, rgba(11,14,15,0.95) 0%, rgba(11,14,15,0.2) 60%, rgba(11,14,15,0) 100%); }
.tile-body { position: relative; z-index: 1; padding: 28px 28px 32px; }
.tile-body h3 { font-family: var(--f-mono); font-size: 14px; font-weight: 500; letter-spacing: 0.2em; display: flex; align-items: center; margin-bottom: 12px; }
.tile-body p { margin: 0; font-size: 16px; }
.layer-note { margin: 0; padding-top: 28px; border-top: 1px solid var(--line); color: var(--mute); }

/* asset */
.asset { display: grid; grid-template-columns: 240px 1fr; gap: clamp(32px, 6vw, 96px); align-items: center; }
.asset-node { position: relative; width: 220px; aspect-ratio: 1; display: grid; place-items: center; }
.asset-node svg { position: absolute; inset: 0; width: 100%; height: 100%; fill: none; stroke: var(--paper); stroke-width: 1.2; }
.asset-node .tag { position: absolute; top: 28%; font-family: var(--f-mono); font-size: 22px; font-weight: 500; }
.asset-node .tag-sub { position: absolute; top: 56%; font-size: 14px; color: var(--mute); }
.asset-cards { display: grid; grid-template-columns: 1fr 1fr; gap: 1px; background: var(--line); border: 1px solid var(--line); }
.asset-card { background: var(--ink); padding: 36px 32px 40px; }
.asset-card h3 { margin-bottom: 14px; }
.asset-card p { margin: 0; color: #c5cdcb; }
.asset-note { margin: 40px 0 0; color: var(--mute); }

/* ai */
.section-ai { display: grid; grid-template-columns: 1fr 1.1fr; gap: clamp(32px, 6vw, 96px); align-items: start; }
.section-ai .section-head { margin-bottom: 0; }
.section-ai h2 { font-size: clamp(30px, 3.6vw, 52px); }
.console { margin: 0; background: var(--panel); border: 1px solid var(--line); padding: 0 0 20px; }
.console-bar { display: flex; justify-content: space-between; align-items: center; padding: 12px 20px; border-bottom: 1px solid var(--line); font-family: var(--f-mono); font-size: 11px; letter-spacing: 0.2em; color: var(--mute); }
.console-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--pid); }
.q { margin: 24px 20px 20px; padding: 14px 18px; background: var(--paper); color: var(--ink); font-size: 15px; }
.calls { list-style: none; margin: 0 20px; padding: 0; border-top: 1px solid var(--line); }
.calls li { display: grid; grid-template-columns: 150px 1fr 18px; align-items: center; gap: 12px; padding: 11px 0; border-bottom: 1px solid var(--line); font-size: 14px; }
.calls code { font-family: var(--f-mono); font-size: 13px; color: var(--paper); }
.calls span { color: var(--mute); }
.calls .sw { margin: 0; }
.a { margin: 20px 20px 0; font-size: 15px; }
.a p { margin: 0; }
.refs { display: flex; flex-wrap: wrap; gap: 8px; margin-top: 14px !important; }
.refs span { font-family: var(--f-mono); font-size: 12px; color: var(--mute); border: 1px solid var(--line); padding: 2px 10px; }
.console figcaption { margin: 20px 20px 0; font-size: 12px; color: var(--mute); }

/* contact */
.contact { max-width: var(--max); margin: 0 auto; padding: clamp(112px, 14vw, 200px) var(--gutter); }
.contact p { color: #c5cdcb; margin: 28px 0 40px; max-width: 40em; font-size: 17px; }

/* 図書：左の図書の山から、構造化して右の二つへ */
.docmap { display: grid; grid-template-columns: 1fr 96px 1.25fr; align-items: center; }
.docmap-src { display: flex; flex-wrap: wrap; gap: 8px; }
.docmap-src span { font-size: 14px; padding: 6px 12px; border: 1px solid var(--line); color: #c5cdcb; background: var(--panel); }
.docmap-src .more-docs { border-style: dashed; color: var(--mute); background: none; }
.docmap-arrow { position: relative; height: 2px; margin: 0 12px; background: var(--paper); }
.docmap-arrow::after { content: ""; position: absolute; right: -2px; top: -5px; border: 6px solid transparent; border-left: 9px solid var(--paper); }
.docmap-arrow span { position: absolute; left: 50%; bottom: 10px; transform: translateX(-50%); font-family: var(--f-mono); font-size: 11px; letter-spacing: .12em; color: var(--mute); white-space: nowrap; }
.docmap-dst { display: grid; gap: 1px; background: var(--line); border: 1px solid var(--line); }
.docmap-dst article { background: var(--ink); padding: 24px 24px 26px; }
.docmap-dst h3 { font-size: 19px; margin-bottom: 8px; }
.docmap-dst p { margin: 0 0 14px !important; font-size: 15px !important; line-height: 1.8 !important; color: #c5cdcb; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; }
.chips span { font-size: 13px; padding: 2px 10px; border: 1px solid var(--line); color: var(--paper); }
.chips .chip-tag { font-family: var(--f-mono); border-radius: 999px; }
/* 解説ページの本文の中では縦に積む */
.doc-body .docmap { margin-top: 40px; grid-template-columns: 1fr; }
.doc-body .docmap-arrow { width: 2px; height: 56px; margin: 16px 0 16px 40px; }
.doc-body .docmap-arrow::after { right: -5px; top: auto; bottom: -4px; border: 6px solid transparent; border-top: 9px solid var(--paper); }
.doc-body .docmap-arrow span { left: 16px; bottom: 50%; transform: translateY(50%); }

/* ---------- 解説ページ ---------- */
.doc-hero {
  position: relative; min-height: min(72svh, 720px);
  display: flex; align-items: flex-end;
  padding: 120px var(--edge) 80px; overflow: hidden;
  border-bottom: 1px solid var(--line);
}
.doc-hero::after { content: ""; position: absolute; inset: 0; background: linear-gradient(90deg, rgba(11,14,15,0.92) 0%, rgba(11,14,15,0.6) 55%, rgba(11,14,15,0.2) 100%); }
.doc-hero-inner { position: relative; z-index: 1; max-width: 860px; }
.doc-hero h1 { font-size: clamp(32px, 4.8vw, 64px); }
.doc { max-width: var(--max); margin: 0 auto; padding: 0 var(--gutter); }
.doc-sec {
  display: grid; grid-template-columns: 200px minmax(0, 720px); gap: clamp(24px, 5vw, 80px);
  padding: clamp(64px, 8vw, 112px) 0; border-bottom: 1px solid var(--line);
}
.doc-label { margin: 6px 0 0; font-family: var(--f-mono); font-size: 13px; letter-spacing: 0.16em; color: var(--mute); }
.doc-body h2 { font-size: clamp(24px, 2.6vw, 34px); line-height: 1.45; margin-bottom: 28px; }
.doc-body p { margin: 0 0 1.4em; font-size: 17px; line-height: 2; color: #d3dad8; }
.doc-body p:last-child { margin-bottom: 0; }
.doc-figure { margin: 48px 0 0; padding: 32px; background: var(--panel); border: 1px solid var(--line); }
.doc-figure svg { display: block; width: 100%; max-width: 520px; height: auto; margin: 0 auto; }
.doc-figure figcaption { margin-top: 20px; font-size: 13px; color: var(--mute); }
.doc-questions { list-style: none; margin: 0 0 1.6em; padding: 0; border-top: 1px solid var(--line); }
.doc-questions li { padding: 14px 0 14px 28px; border-bottom: 1px solid var(--line); position: relative; font-size: 16px; }
.doc-questions li::before { content: "Q"; position: absolute; left: 0; top: 14px; font-family: var(--f-mono); color: var(--pid); }
.doc-merits { display: grid; grid-template-columns: repeat(3, 1fr); gap: 1px; background: var(--line); border: 1px solid var(--line); }
.doc-merits > div { background: var(--ink); padding: 28px 24px; }
.doc-merits h3 { font-size: 18px; margin-bottom: 12px; }
.doc-merits p { font-size: 15px; line-height: 1.8; margin: 0; }
.nav a[aria-current="page"] { color: var(--paper); }

/* ---------- footer: title block ---------- */
.titleblock {
  display: grid; grid-template-columns: 1.3fr 2.4fr repeat(4, 1fr);
  border-top: 1px solid var(--line);
  font-family: var(--f-mono); font-size: 13px;
}
.tb-cell { padding: 14px 18px 18px; border-right: 1px solid var(--line); }
.tb-cell:last-child { border-right: 0; }
.tb-title { font-family: var(--f-body); }
.tb-label { display: block; font-family: var(--f-mono); font-size: 10px; letter-spacing: 0.2em; color: var(--mute); margin-bottom: 4px; }

/* ---------- responsive ---------- */
@media (max-width: 900px) {
  .docmap { grid-template-columns: 1fr; }
  .docmap-arrow { width: 2px; height: 56px; margin: 16px 0 16px 40px; }
  .docmap-arrow::after { right: -5px; top: auto; bottom: -4px; border: 6px solid transparent; border-top: 9px solid var(--paper); }
  .docmap-arrow span { left: 16px; bottom: 50%; transform: translateY(50%); }
  .doc-sec { grid-template-columns: 1fr; gap: 12px; }
  .doc-merits { grid-template-columns: 1fr; }
  .platform, .asset, .section-ai { grid-template-columns: 1fr; }
  .tiles { grid-template-columns: 1fr; }
  .tile { aspect-ratio: 1 / 1; }
  .tile-net { height: 62%; }
  .asset-node { width: 180px; }
  .titleblock { grid-template-columns: repeat(4, 1fr); }
  .tb-brand, .tb-title { grid-column: span 4; border-right: 0; border-bottom: 1px solid var(--line); }
}
@media (max-width: 640px) {
  .nav a:not(.nav-cta) { display: none; }
  .hero { padding-bottom: 72px; }
  .hero::after { background: linear-gradient(0deg, rgba(11,14,15,0.95) 0%, rgba(11,14,15,0.6) 55%, rgba(11,14,15,0.2) 100%); }
  .asset-cards { grid-template-columns: 1fr; }
  .calls li { grid-template-columns: 1fr 18px; }
  .calls li span { grid-column: 1; grid-row: 2; }
  .calls li .sw { grid-row: 1 / span 2; grid-column: 2; }
}
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  .tile img { transition: none; }
}